In the transmission of a color picture, the transmitting source and the receiving device must both be synchronized to a common frequency carrier in order that the color information of the picture be properly reproduced. Thus, in addition to the picture information, color synchronizing information must be transmitted simultaneously. In a color television system, the color synchronizing information is transmitted as a signal known as the "color burst". The color burst is used with appropriate standard circuits to synchronize an oscillator in the television receiver.
The color transmission systems used (NTSC standards), when properly modulated and demodulated, result in four distinct signals which are available simultaneously in the TV receiver from a single incoming signal. These four signals are:
A. Luminance information (black and white instantaneous brightness)
B. Red chroma excitation level
C. Green chroma excitation level
D. Blue chroma excitation level
Each one of these signals can be derived independently of the other by proper demodulation techniques. The approximate bandwidth for luminance is 2 MHz and for each chroma signal is 0.5 MHz.
It is an object of the present invention to utilize these signals for encoding digital information and then incorporating these encoded signals within the transmission of a standard television picture. It is a further object of the present invention to incorporate these encoded signals during a specific portion of the television signal, namely, during the vertical interval of the television signal.